The invention relates to an inverter for an electric machine.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
The electric machine serves for example for driving the motor vehicle, i.e., for providing a torque that is directed towards propulsion of the motor vehicle. Because an onboard network of the motor vehicle usually provides a DIC current but the electric machine is constructed as an A/C current machine or three-phase machine, the inverter is provided. The inverter serves for converting the DIC current into A/C current or three-phase current. The inverter is for example constructed as a pulse inverter or as an H-bridge.
The inverter has the intermediate circuit or is at least connected to the intermediate circuit. The intermediate circuit includes the first electrical pole and the second electrical pole, which have different potentials compared to teach other. For example the first electrical pole is a plus pole and the second electrical pole is a minus pole. The inverter also includes the multiple phase systems, i.e., at least two phase systems (in the case of conversion of a DIC current into NC current) or at least three phase systems (in the case of conversion into a three phase current). Each of the phase systems has a high-side switching device and a low-side switching device, which are connected in series with each other and are connected on one side to the first electrical pole and on the other side to the second electrical pole.
In other words the high-side switching device is thus connected on one side to the first electrical pole and on the other side to the low-side switching device, while the low-side switching device is connected on one side to the high-side switching device and on the other side to the second electrical pole. Each of the switching devices, i.e., the high-side switching device as well as the low-side switching device, has a circuit breaker which has the power input and the power output. When a voltage is present at the switching input or an electrical current flows from the switching input to the power output the circuit breaker closes, so that the power input is eclectically connected with the power output. When on the other hand the switching input is without voltage or without current the circuit breaker is open and correspondingly the power input and the power output are electrically separated from each other.
The circuit breaker is for example a transistor, in particular a bipolar transistor or a field effect transistor. The field effect transistor can hereby be configured as a bipolar transistor with insulated gate electrode (IGBT), the field effect transistor as barrier junction field effect transistor or as a metal insulator semiconductor field effect transistor (MISFET) or a field-effect transistor with a gate, which is separated by an insulator (IGFET). Of course the circuit breaker can also have an alternative configuration.
More concretely regarding the above description the power input of the circuit breaker of the high-side switching device is permanently connected with the first electrical pole, while its power output is permanently connected with the power input of the circuit breaker of the low-side switching device. The power output of the low-side switching device is permanently connected with the second pole. Between the high-side switching device and the low-side switching device a phase connection for the electric machine can be provided, in particular an electrical connection of the electric machine is connected between the high-side switching device and the low-side switching device.
It would be desirable and advantageous to provide an inverter for an electric machine that has advantages compared to known inverters and that can in particular be operated reliably also in case of an error.